优化 撤回处理的代码

pmapi/src/main/java/com/ningdatech/pmapi/todocenter/manage/TodoCenterManage.java

@@ -180,6 +180,7 @@ public class TodoCenterManage {
             return PageVo.empty();
         }
 
+        todoList = todoList.stream().filter(Objects::nonNull).collect(Collectors.toList());
         List<ProcessTaskVo> userTodoList = todoList.stream()
                 .skip((long) (pageNumber - 1) * pageSize)
                 .limit(pageSize)